I just had all tune up parts, the timing belt, 02 sensor, valve cover gasket, water pump, fuel filter, water pump, air filter, belts, valve cover gasket, coolant sensor, air box thermostat, fuel pressure regulator, and mass airflow sensor replaced. The mechanic who did most of the work said he could do no more. My regular mechanic, who, meanwhile, returned from winter break, checked the car over and said it the problem was either with a cheap wire set (not cheap money wise, I'll say) or "the computer." At this point, $3,000 later, I am getting involved. Given the above symptoms, what computer could my regular mechanic be talking about, the Ignition Control Module or the Fuel Injection Computer? And which one of these is the same as the "ECU?" How many computers does the car have? The car also had an undesirable smell that was bothering me for a long time that has been overcome by the new, more noxious smell. My regular mechanic claims it is the catalytic converter, but I have no power issues. The other mechanic claims that it isn't the catalytic converter, as does the dealer. I mean, what is up? Someone on this site (Fitz) says to avoid platinum plugs. Which ones to get? I must replace them every two days right now so that the car will run. Which wires to get as well. Oh and which "Computer." Any expert and experienced help I could get at this point would be greatly appreciated.

Three grand?!? I think I would remind this mechanic that his fees are for competent diagnostics performed to industry standard as well as just randomly replacing parts, a fact that often stands in small claims court...

Stop swapping parts and start measuring. Put in a new set of copper plugs gapped to spec (Bosch or NGK) so that it will run while you diagnose.

Pull the OBD codes as others have suggested. There may be meaningful clues there. More often than not they provide clues rather than "smoking guns" in my experience...

Measure fuel pressure at the rail. Pull the vacuum line at the front of the regulator and smell/look for fuel. I know the part is new, but not all new parts are good. See if you have fuel bypassing out to the return line (back of regulator). You have rich running symptoms (gassy, missing, hard start, black exhaust) that point to FPR, ECT sensor stuff.

Get a noid light and see if you get consistent flashes at the injector harnesses. If you do, it is much less likely that need a new ECU. If the injector function is flaky you may have a problem with the power stage, although the classic failure mode is poor running/stalling/no-start when hot.

Check spark on all 4 cylinders-- you can use a spark plug or a spark tester. If you get consistent bright spark your ignition system is OK (as is your RPM sensor). Inconsistent spark could be the RPM sensor, or the wires. If you need wires, buy Bougicord.

Measure the output of your new coolant temp sensor at the ECU as per the 700/900FAQ. Did the mechanic replace the forward sensor (gauge) or the one between runners 3&4 on the intake that actually talks to the computer? Bad connections or a bad part here could cause the car to run really rich and foul the plugs in short order. Bad contacts in the ECT harness plugs are reported here from time to time.

Pull the timing belt cover and verify the engine timing as per the 700/900FAQ.

Bypass the fuel system relay and see if the car runs better-- search the archive for lucid's method of jumpering fuse 4 & 6. Or replace the relay to see if the running improves.

If the car has been running rich for a long time the cat may well be toast. FCPgroton.com has them for about $130-- I had to put one on my '92 245 before I sold it-- it was a Canadian made Davico and it seemed like a good part. If you have been smelling a "rotten egg" smell, it is quite likely the cat is cooked. Just replacing it isn't going to fix anything, though-- you need to find out what made the car run rich and kill it or you will need one again by the next emissions test.

Measure the output of the sensor line on your 02 sensor with a volt/ohm meter. I'll bet it is pegged on the rich side rather than fluctuating between .15 and .85VDC. I had a new Bosch sensor that was putting out 1.4V, which made the car run just terribly. Some have suggested that this can be caused by stray voltage from the heater circuit.

Have a close look at the connector wiring for the AMM. Did you get a new or a rebuilt AMM? Which LH system does your car have? It is either LH2.4 or LH3.1, and this will determine what AMM you need. Does the car idle better with the AMM unplugged?

The advice on setting up the throttle body is good too. Make sure the idle air motor and the throttle position switch harnesses weren't swapped.

Check for vacuum leaks at the intake manifold, look for holes in the intake snorkel and check all the vacuum lines.

Check which ECU you have-- if it is a pink label -561 (the last 3 digits of the part number), it is a known problem ECU. White label -561 or a -951 are better. The ignition computers (ICU) seem quite robust. The ECU usual failure is no grounding of the injectors, so no noid light flashing, so don't go buy one without checking injector function unless you have access to a used one cheap that you can prove is good.

I am sorry to hear about your troubles-- report back on your measurements and you will get help from a lot of smart people here. I am continually amazed at how helpful brickboarders are!

Good luck!

Herb, Thanks much for your input. My concern is what else will get goofed up before I get this thing tied down. I really, really appreciate your advice. Thanks.

My opinion is that you need to get away from these guys-- unless they are offering some sort of remediation on pricing for the work to date-- having them eat the mark-up on some of the parts seems reasonable. I also had a look at the dealer parts pricing-- the mark-ups were atrocious-- the FPR from online sources will run you $53, not $176, and $300+ for an 02 sensor is equally gruesome when a $39 part will do the trick. What is this place called? BenDover Volvo?

My opinion is that our RWD Volvos should be serviced by a Volvo independent shop for all the things you can't or don't want to do yourself. Chances are you will find one that is staffed by mechanics who worked in the dealerships when these cars were new. They know the ropes better than the current techs in the stealerships (hence the reference to the "front" 02 sensor-- I'll pay your bill if you can show me the back sensor!).

Best of luck-- post back with diagnostics and hopefully you will get things sorted out quickly and for little additional investment.

Get a noid light and see if you get consistent flashes at the injector harnesses.

Please educate me. I have a 12V light. Are you saying to Clip one side of teh light to ground and with the Injector connector off the Injector to probe one side and look for a constant,even flash?

I may need this knowledge someday.
Thanks
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Hi Tony:

The 'noid light (an LED and some resistors, by the looks of things) plugs into the injector harness. If the light pulses during cranking/running, the electrical components driving the injectors are good. It is a good way to look check for ECU failure as well as other components in that pathway-- the classic failure mode for the -561 ECU is to fail to ground the injectors.

I understand iPd sells the specific 'noid light for the Bosch, and I'd bet that you could borrow one as part of the tool loaner program at places like AutoZone-- you can borrow a kit here in Canada from Partsource (like AutoZone, only twice as expensive with worse service).

Cheers!

Ahh, so it is a specific tool. I thought maybe it was just an idiot light to ground and a 12V pulse through the connector to ground would show power to the Injector.

There may be more 'magic' in the specific tool.

Thanks Herb
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Bad air mass meter (AMM) connector? Try unplugging the AMM, then starting the car... any improvement? Before reconnecting the AMM connector, be sure you can see all 6-pins (I think there's 6!), and be sure they're all clean. Just for kicks, what part number is on the AMM?

Check for OBD codes (see the 700/900 FAQ on this--same thing in the 240). Swapping a used computer in could be worth a try.

Get Bosch or NGK copper plugs. The Bosch number is in your owners manual, the NGK, I don't know. Bougicord is the brand of plug wires to get.

-Ryan
--

Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club

I'll try the AMM procedure. Thanks for the plug info - that is what I just got because they foul to useless every fifty miles at present. The car runs much better, relatively speaking.

Ian ['93 240W/BGM, 189k]

Are you having these problems after all these parts were added or is this issue the reason for the Extensive Tune up?

Gassy smell, fouling plugs, sounds like Fuel pressure Regulator but you state that it was replaced.

The Valve Cover Gasket was replaced... Did the Ground Strap from the Firewall to the Valve Cover make it back on?????
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

After. My second mechanic said all the parts were good save for the wires. I had a smell but it I had no starting or running problems associated with it - just the smell, interestingly. I don't know at this time if the ground strap made it back on. Neither mechanic mentioned it.

Thanks a lot for your advice.

Ian ['93 240W/BGM, 189k]

I think a good 240 mechanic could get your car running well with almost no other money spent on parts. IMHO. A few baseline things need to be done/checked 1. Timing belt properly installed/cam timing correct 2. Throttle body butterfly properly adjusted and cleaned 3. throttle position switch properly adjusted 4. fuel injection grounds at engine fuel rail cleaned 5. a known good fuel pump relay installed 6. what is the fuel pressure like on a gauge? Other things could be done for sure, if more info was known. Are your mechanics just throwing parts at this car, or do they know what they are doing? For instance, why was a new fuel pressure reg installed, exactly? The ECU would be the fuel injection computer, and you are right, there are two computers fuel and injection. What codes does the computer spit out when you do a diagnostic check?
Charles

The dealer ran the computer check because the original mechanic did not have one. They wrote: Scan DTC code 113, 221, 231 fuel trim codes; backprobe 02 sensor. No voltage signal from MAF; Check MAF sensor ok; found fuel pressure regulator leaking past diaphragm. See recommendations. Diagnosis only. Recommendations: Fuel Pressure Regulator: $176.10; MAF Sensor and Air Box Thermostat: $516.10; Spark Plugs: $92.08 [not a typo] May need front 02 sensor: $355.10.

Thanks much,

Ian ['93 240W/BGM, 189k]

"The dealer ran the computer check because the original mechanic did not have one."
Better avoid that "original mechanic" because the code readout is under the hood and a simple procedure to extract codes. See 700/900 FAQ for OBD code procedure.

"May need front 02 sensor: $355.10"
There's only one O2 sensor that I know of, or can find on wiring diagram.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Correction- two computers, fuel and ignition
Charles